BAS Ozone Bulletin 02/99 issued 1999 September 20
The 1999 ozone hole now covers virtually all of Antarctica with minimum ozone values decreasing steadily. Lowest values currently extend over the broad region from the Weddell Sea to Wilkes Land. The edge of the ozone hole is expected to swing towards the tip of South America over the next 48 hours. Total ozone values at Vernadsky dropped below 170 DU during early September, nearly 50% below the normal for the time of year. Total ozone values at Halley have dropped below 150 DU, 50% below the normal for the time of year.
1. Data from the British Antarctic Survey (BAS) Halley station (76-deg south, 27-deg west, on the Brunt ice shelf).
Halley preliminary mean daily total ozone, (DU)
Dobson No 103: Instrument constants revised 1999 September 17.
(0 indicates no data)
1999 August 21 - 1999 September 16
Note that August and April do not have observations on every day, and that the routine measurement season is now longer than it was in 1957 - 72. Measurements made at the start of the season are of lower accuracy than in mid summer due to the low solar elevation or use of moonlight. Gif images showing the data are available on the BAS ozone web-page.
2. Data from the British Antarctic Survey (BAS) Rothera station (68-deg south, 68-deg west on Adelaide Island).
Rothera preliminary mean daily total ozone, (DU)
(0 indicates no data or data not available)
1999 July 1 - 1999 September 14
299 313 281 270 267 290 0 258 260 260 210 228 239 256 249 243 200 232 262 239 225 222 219 224 241 214 210 210 225 219 223
186 175 0 165 164 194 183 162 158 164
154 143 162 167
3. Data from the Ukrainian Antarctic Research Centre Vernadsky station (65-deg south, 64-deg west on the coast of the Antarctic Peninsula, formerly the BAS Faraday station).
Vernadsky preliminary mean daily total ozone (DU).
Dobson No 31: Instrument constants revised 1999 May 10
1999 August 1 - 1999 September 15
291 314 270 270 277 283 257 248 249 260 224 210 225 263 253 259 214 229 227 221
221 239 221 231 235 202 211 226 256 231 249
214 187 174 181 169 0 0 0 167 178
196 191 169 178 228
4. Information from other sources.
TOVS satellite images from the US NCEP/NWS/NOAA Climate Prediction Center and EP/TOMS images from the US NASA/GSFC show the progressive development of the ozone hole. Lowest values are currently over the region from the Weddell Sea to Wilkes Land, with depletion affecting all of Antarctica. UK Met Office 100 hPa forecast charts suggest that the vortex edge will swing past the tip of South America over the next 48 hours. The 100 hPa temperature remains below -80 deg C over much of Antarctica.
Further information is available on the BAS ozone web page, which contains earlier bulletins, data, graphs and general ozone information. The url is:
http://www.nbs.ac.uk/public/icd/jds/ozone
Note that all ozone values in this bulletin are preliminary and are subject to revision from time to time when the instrument constants are re-evaluated. Final data will be archived with WOUDC, Toronto in due course, but preliminary data back to 1973 are available from BAS on request. All Dobson ozone data are reduced to the Bass-Paur scale as recommended by the WMO. The reference period used for the normals is 1957 - 1972. If you use or pass on data in this bulletin please make acknowledgement to J D Shanklin, British Antarctic Survey.
Jon Shanklin